Hopping transport in polythiophene versus poly(phenylene vinylene)

We have studied the hopping transport in two FeCl3 doped conjugated polymers - a poly(phenylene vinylene), PPV, and polythiophene, PTh, derivative. Surprisingly, the conductivity of PPV is orders of magnitude higher than that of PTh at the same doping level. Analysis of the dc conductivity and high frequency (0.03-10 THz) response as a function of temperature, enables us to account for these differences. While in PTh carriers are strongly localized onto quasi-1D chains, the higher interchain overlap in PPV provides an effectively 3D conductive structure. Especially the data above 0.1 THz are very illustrative for the almost metallic contact between the PPV chains